1. Field of the Invention
This invention relates to an adjustable wheel assembly and more particularly to an adjustable wheel assembly for an agricultural tractor.
2. Description of the Prior Art
One of the necessary features on an agricultural tractor is the ability for the operator to adjust the wheel spacing so as to perform various farm operations. Typically, the drive wheels on a tractor are adjusted to match a particular farming operation. For example, when plowing, it is advantageous to keep the line of draft of the implement in alignment with the center line of the tractor and still have one wheel of the tractor run in the furrow formed by the plow on the previous pass. When cultivating, it is necessary to have the wheels properly spaced to run between the rows of crop. As the operator changes from one type of operation or implement to another, he must adjust the wheel spacing to suit the new function or implement.
Since the wheels of a tractor are quite heavy, particularly when loaded with wheel weights or filled with a liquid solution for weighting purposes, it is advantageous that the tractor contain an easily adjustable wheel assembly. This wheel assembly should be functional even when a tractor's axle and associated wheel attaching components are coated with an accumulation of rust and mud. Most of the currently available wheel assemblies are constructed in such a way that it is extremely difficult for the operator to release the wheel hub from the axle under these conditions. In fact, the buildup of rust and mud on the wheel hub can require high wrench torque forces to break the bolts loose before adjustment of the wheel on the axle can be made.
Previous attempts to rectify such wheel adjustment problems have led to a variety of mechanisms. Two of these mechanisms are described in the following U.S. Pat. Nos. 2,676,849, issued in April 1954 to G. H. Houck et al and 3,279,831, issued in October 1966 to G. E. Smelcer et al. The first of these two patents, the Houck patent, teaches a wheel assembly using two tapered semicircular wedge-like structures which are inserted about the axle and are bolted to the wheel hub. Such a design is both difficult to manufacture because of the length of the two tapered wedges and often is hard to disassemble since the two long tapered wedges have more surface area on which to rust onto the wheel hub. Applicant's new invention minimizes the manufacturing problems and overcomes the buildup of rust by using a plurality of shorter arc-shaped wedges containing a smaller taper length. By shortening the length of the taper, closer manufacturing tolerances can be obtained which reduce the presence of air pockets and thereby minimize rust buildup.
The Smelcer patent teaches another method of mounting a tractor wheel to an axle. This particular method uses recesses formed in both the axle and the wheel hub which together contain multiple drive transmitting means. The drive transmitting means include elongated key members disposed in the recesses so that the wheel hub will turn with the axle. The Smelcer patent, aside from using axle recesses and elongated key members, is further distinguishable from applicant's invention is that no mechanism is taught for moving the wheel hub axially along the axle after the fastening bolts are loosened. Instead, Smelcer relies on a rocking motion to move the wheel along the axle.
The above two assemblies, along with the other wheel assemblies, have not been altogether satisfactory either because of their inability to be adjusted under field conditions or because functionally they are not adaptable to farming operations. These disadvantages are overcome by the present invention.
The general object of this invention is to provide an adjustable wheel assembly for an agricultural tractor. A more specific object of this invention is to provide an adjustable wheel assembly with easy adjustability without requiring high wrench torque forces.
Another object of this invention is to provide an adjustable wheel assembly which uses a greater contact area between the wheel hub and the axle, thereby improving adjustability.
Still another object of this invention is to provide an adjustable wheel assembly having two pairs of arc-shaped wedges which provide a more controllable contact surface for the outer edges of the wheel hub while being less sensitive to tolerance variations.
A further object of this invention is to provide an adjustable wheel assembly which is reversible so that two wheels can be placed side by side on a single axle.
Still further, an object of this invention is to position an adjusting means in one of the arc-shaped wedges so that one size wheel hub can fit various size axles.
Other objects and advantages of the present invention will become more apparent when considered in connection with the specification and the drawings.